In this lab we will look at the minimum configuration required to build a redundant and high speed link between two Cisco switches.
Configuration
SW1(config)#interface range gigabitEthernet 0/0-1 ! SW1(config-if-range)#channel-protocol ? lacp Prepare interface for LACP protocol pagp Prepare interface for PAgP protocol SW1(config-if-range)#channel-protocol lacp ! SW1(config-if-range)#channel-group ? <1-255> Channel group number auto Enable LACP auto on this interface ! SW1(config-if-range)#channel-group 1 ? mode Etherchannel Mode of the interface ! SW1(config-if-range)#channel-group 1 mode ? active Enable LACP unconditionally auto Enable PAgP only if a PAgP device is detected desirable Enable PAgP unconditionally on Enable Etherchannel only passive Enable LACP only if a LACP device is detected ! SW1(config-if-range)#channel-group 1 mode active Creating a port-channel interface Port-channel 1 ! SW2(config)#interface range gigabitEthernet 0/0-1 ! SW2(config-if-range)#channel-protocol lacp SW2(config-if-range)#channel-group 1 mode active
Depending on your requirements you will need to use either active or passive.
Verification
SW1#
*Oct 26 05:08:04.210: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to up
*Oct 26 05:08:04.220: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/1, changed state to up
*Oct 26 05:08:07.008: %LINK-3-UPDOWN: Interface Port-channel1, changed state to up
*Oct 26 05:08:08.008: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to up
!
SW1#show etherchannel summary
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use N - not in use, no aggregation
f - failed to allocate aggregator
M - not in use, minimum links not met
m - not in use, port not aggregated due to minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
A - formed by Auto LAG
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SU) LACP Gi0/0(P) Gi0/1(P)
!
SW1#show etherchannel detail
Channel-group listing:
----------------------
Group: 1
----------
Group state = L2
Ports: 2 Maxports = 4
Port-channels: 1 Max Port-channels = 4
Protocol: LACP
Minimum Links: 0
Ports in the group:
-------------------
Port: Gi0/0
------------
Port state = Up Mstr Assoc In-Bndl
Channel group = 1 Mode = Active Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = LACP
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Gi0/0 SA bndl 32768 0x1 0x1 0x1 0x3D
Partner's information:
LACP port Admin Oper Port Port
Port Flags Priority Dev ID Age key Key Number State
Gi0/0 SA 32768 0c73.d669.8000 7s 0x0 0x1 0x1 0x3D
Age of the port in the current state: 0d:00h:04m:35s
Port: Gi0/1
------------
Port state = Up Mstr Assoc In-Bndl
Channel group = 1 Mode = Active Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = LACP
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Gi0/1 SA bndl 32768 0x1 0x1 0x2 0x3D
Partner's information:
LACP port Admin Oper Port Port
Port Flags Priority Dev ID Age key Key Number State
Gi0/1 SA 32768 0c73.d669.8000 1s 0x0 0x1 0x2 0x3D
Age of the port in the current state: 0d:00h:04m:33s
Port-channels in the group:
---------------------------
Port-channel: Po1 (Primary Aggregator)
------------
Age of the Port-channel = 0d:00h:07m:17s
Logical slot/port = 16/0 Number of ports = 2
HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = LACP
Port security = Disabled
Ports in the Port-channel:
Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Gi0/0 Active 0
0 00 Gi0/1 Active 0
Time since last port bundled: 0d:00h:04m:33s Gi0/1
!
SW1#show interfaces status
Port Name Status Vlan Duplex Speed Type
Po1 connected 1 a-full auto 
